Department of Biological Sciences OCB 2003L
Lab #5: Evolution of Appendages and Feeding Behavior
Lab objective: Understand the differences between invertebrates in their general body morphology and how these differences impact their feeding and locomotive behaviors
Pre-lab assignment: Read Invertebrate Comparative morphology handout
Task #1: Echinodermata Tube Feet
As a team, go out into the bay and collect one Atlantic purple sea urchin from the rocks near the beach area. Return to lab and place this urchin underneath the dissecting scope with the light off for 10 minutes. After 10 minutes, turn the light on and look at the urchin under the microscope. Observe and record the movement of the spines and tube feet in response to touching through the use of a probe.
What is the importance of the tube feet structures?
Task #2: Cnidarian vs. Molluscan tentacles
Place the live anemone underneath the dissecting scope. Observe the tentacles in response to water movement and touching through the use of a probe.
How does the anemone’s response differ from the sea urchin?
Obtain a squid from your instructor. Consider the squid in comparison to the anemone.
How are their feeding tentacles different?
What types of structures do Molluscan tentacles have that Cnidarian tentacles do not?
What types of structures do Cnidarians tentacles have that Molluscan tentacles do not?
What are some advantages of each type of feeding structure? Disadvantages?
Task #3: Arthropoda appendages
Review the figures of feeding appendages contained in the handout.
Consider the provided specimens: Horseshoe crab, crayfish and true crab
What characteristics are similar among all three specimens?
What characteristics are different among all three specimens?
Describe how each specimen’s appendages provide information about how the animal survives in its environment.
What are some advantages of each type of feeding appendage?
What are some disadvantages of each type of feeding appendage?
Task #4: Squid Dissection
Draw the external anatomy of your squid and label the following: arm, tentacle, eye, funnel, fin, mantle
(Use the whole space!)
Draw the internal anatomy of your squid and label the following: gill, ink sac, caecum
(Use the whole space!)
How many arms does your squid have? How many tentacles?
Based on the structure of the arms and the tentacles, describe how their purposes differ. What do the arms do and what do the tentacles do?
Draw arrows on the squid below to indicate the direction that water comes out of the funnel and the direction that the squid moves.
Name two external features that are adaptations for the squid’s predatory life. How do these adaptations help the squid?
What is the function of the pen? What would happen if the squid didn’t have a pen?